Corrected module configuration in acceptance.suite.yml

previously it was written like 

```
modules:
   enabled: [Selenium2]
   config:
      Selenium2:

```
which was changed to WebDriver module as 

```
    modules:
       enabled: [WebDriver]
       config:
          WebDriver:
```
Merge pull request #549 from aditya-/patch-1

Corrected module configuration in acceptance.suite.yml in WebDriver module